Grate bar



G. K. DREHER Dec. 27, 1966 GRATE BAR 2 Sheets-Sheet l Filed June 30, 1965 l N VENTOR.

A TTU/IgE YS lmhlm G. K. DREHER GRATE BAR 2 Sheets-Sheet 2 Filed June 30, 1965 INVENTUR. @06625 K @ef/22C@ 1%/ ,f ATTORNEYS United States Patent O 3,294,044 @RATE BAR George K. Dreher, Fiossmoor, Ill., assignor to Burnside Steel Foundry Company, Chicago, lll., a corporation of Iliinois Filed .lune 30, 1965, Ser. No. 468,457' Claims. (Cl. 11G-d0) This invention relates `to improvements in grates and more particularly relates to an improved form of traveling grate subjected to high temperatures over a relatively long period of time.

In the drying or ring of green iron concentrate pellets, the green pellets are discharged onto a traveling grate, which may be from 70 to 90 feet long or longer, and conveys the pellets through a furnace usually having an initial preheat zone of a temperature range between 500 to 600 F. into which the green pellets are initially discharged, a relatively long drying and firing zone, where the pellets are both dried and fired, the temperature of which is in the order of 2000 F., and which takes up a greater part of the length of the furnace. From the drying Zone the grate conveys the fired pellets through a cooling zone, where the pellets are discharged for further treatment. The changes in temperature as the grate passes from one zone to the other, as well as the extreme temperatures in the drying firing zone, caused by the heated air passing through the grates presents an expansion and contraction problem of the grates, resulting in frequent damage to the grates and shortening the life of the grates to the extent that they must frequently be replaced.

A principal object of the present invention is to overcome the foregoing difficulties by providing a freely expansible grate bar in which the grate fingers are isolated from their supports.

Another object of the invention is to provide a new and improved grate particularly adapted for use in drying iron concentrate pellets, in which the supports for the grate fingers are relatively small in cross-sectional area and are spaced from the grate fingers to accommodate free expansion and contraction of the grate fingers, without materially affecting the supports.

A still further object of the invention is to provide a novel form of grate bar having a plurality of parallel spaced grate fingers spaced above the supports therefor, and so arranged as to freely expand and contract independently of each other.

A still further object of the invention is to provide a simple and improved form of grate, subjected to relatively high temperatures in the order to 2000 F. in which a plurality of parallel spaced elongated grate fingers are supported on a support bar of a relatively small cross-sectional area in comparison with the cross-sectional area of the fingers and remote from the fingers, to free the supports from the expansion and contraction effects of the fingers.

A still further object of the invention is to provide an improved form of grate bar adapted to be slidably placed on a traveling carriage and including a plurality of parallel spaced grate fingers with end frame members spaced forwardly and rearwardly of the fingers, and support bars connected between the end frame members beneath the upper margins thereof with legs extending vertically of the support bars and supporting the fingers in vertically spaced relation with respect to the support bars, in which one end frame member is slit to accommodate expansion and contraction thereof and the grate bars are alternately arranged on their carriages with one slit side frame member leading the next adjacent side frame member trailing to accommodate free expansion thereof for the full length of the carriage.

@,Ziiilid Patented Dee. 2?, 1966 ICC These and other objects of the invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings where- 1n:

FIGURE 1 is a diagrammatic view in side elevation of a firing furnace for green iron concentrate pellets and the like;

FIGURE 2 is a plan view of a grate constructed in accordance with the principles of the present invention;

FIGURE 3 is a side view of the grate shown in FIG- URE 2;

FIGURE 4 is a transverse sectional view taken substantially along line IV-IV of FIGURE 3;

FIGURE 5 is a fragmentary side View showing the grate supported on a traveling carriage, and showing part of the carriage broken away; and

FIGURE 6 is a plan view of a series of grates arranged in side by side relation with respect to each other and supported on a traveling carriage, with part of the carriage broken away.

In the embodiment of the invention illustrated in the drawings, I have diagrammatically shown in FIGURE 1 a drying and firing furnace 10 having a grate 11 traveling therealong. The grate 11 is carried on a carriage 12, mounted for movement along the furnace on wheels 13, 13 and suitably connected with parallel laterally spaced endless chains 15 changing their directions of travel at opposite ends of the furnace about sprockets 16, 16. The sprockets 16, 16 may be driven to progress the grates along the furnace along a preheat Zone A, a drying and firing zone B and a cooling zone C. The endless chains, the drive to the chains and the connection from the chains to the carriages 12 may be of any conventional form, so need not herein be shown or described further.

A conveyor 17 is shown as being provided to discharge green iron concentrate pellets onto the grate 11 in the preheat zone A. A suitable conveyor (not shown) may receive the dried pellets to carry the pellets for further treatment.

The preheat Zone A may be heated to a temperature of between 500 and 600 and may be of a length of approximately 30 feet or longer. The drying and tiring zone A may be heated to a temperature of 2000 F. and may be substantially longer than the preheat zone. The cooling zone C may cool the dry pellets by the circulation of cooled air thereabout and may be of a length substantially equal to the length of the preheat zone. The total length of the furnace and length of the zones A, B and C may, of course, be varied in accordance with drying requirements. The zone B also may be purely a drying zone or may be a drying and baking zone, rather than a drying and firing Zone.

In furnaces of the type diagrammatically shown, the zones A, B and C are usually separated by Ibatiies which extend downwardly across the furnace closely adjacent the bed of pellets on the grate. The green pellets are usually between 3%; and inch in diameter and are heated, dried and fired by the passage of hot gas through the bed of pellets and fiowing in directions counter current to the direction of travel of the grate and pellets through the furnace.

The grate 11 is made up of grate sections 18, which in the present form of the invention may be between nine and twelve inches long and about a foot wide with the sections placed in endwise and side by side relation on the carriage 12. The grate sections, of course, may be of various other practical lengths and widths. The grate sections are preferably castings and each grate section 18 is shown as including a pair of parallel spaced end frame members 19 and 20 connected together beneath the tops thereof by longitudinally extending grate finger support bars 21, 21. Each end frame member 19 and Zt is shown as having an outwardly extending upper flange 22 engageable with and supported on a top surface of a support rail 23 of the carriage 12. The end frame members also each have an outwardly facing vertical wall 24, engageable with the inner side of the associated rail 23. Each wall 24 extends to the bottom of the end frame member for substantially the length thereof and converges in uniform reverse arcs at its opposite ends from the top to the bottom of the wall.

Beneath the flange 22 are spaced retainer gibs 25, shown in FIGURE 2 as forming continuations of the support bars 21, and engageable beneath the rail 23, to retain the carriage and grate to said rail.

The end frame member 29 is herein shown as being transversely slit entirely through the end frame member, as indicated by reference character 27, to accommodate free expansion and contraction of the grate. Alternate outside end frame members of the grate sections may be transversely slit and the grate sections may be arranged along their carriages alternately of each other with a first transversely slit end frame member of a first grate section 1S extending along an advance rail 23 and an opposite transversely slit end frame member 18 of a next succeeding grate section extending along and supported on a trailing rail 23.

A plurality of parallel laterally and longitudinally spaced grate fingers 29, 29 is spaced above the support bars 21, 21 in side by side relation with respect to each other. The grate fingers are shown as tapering inwardly as they extend downwardly and as merging into upright legs 30, 30 extending upwardly from said support bars, and isolating said grate fingers from said support bars. The grate fingers 29, 29 on side by side support bars 21, 21 are also shown as being in alignment with each other and spaced from each other at their adjacent ends. The spacing of the grate fingers from the support bars 19 and 20 `and from each other as well as the width of the slit 27 are such as to accommodate hot fiue V gas to be drawn through the bed of pellets on the grate and to accommodate independent expansion and contraction of the grate fingers 29, 29 with respect to each other and with respect to the end frame members 19 and 20.

The longitudinally extending support bars 21, 21 are relatively narrow in comparison -with the lengths of the grate fingers 29, 29 and the support legs 30 support the grate fingers 29 intermediate their ends, to extend forwardly and rearwardly of said legs. The relatively long grate fingers are thus isolated from the support bars and expansion and contraction of the grate fingers has little if any effect on the support bars.

In FIGURES 5 and 6 I have shown a plurality of grate sections 1S mounted on a carriage 12 by slidable movement onto the rails 23 of the carriage from the ends of the carriage.

I have also shown the grate sections alternately arranged on the carriage with a slit end frame member 20 of one grate section on the advance side of the grate section and a slit end frame member 20 on the next adjacent grate section on the trailing side of the carriage.

It should be understood that the carriage 12 is mounted on the wheels 13 which are supported on rails 45 extending along the furnace, to support the carriages and grate in a level condition for the full extent of its travel through the furnace.

It should also be understood that the carriages are relatively long and wide in comparison with the length and width of the grate sections and that two or more rows of grate sections may be arranged in side by side relation with respect to each other, while three or more grate sections in each row may be arranged in end to end relation with respect to each other. The grate sections also are always spaced closer together than the minimum diameter of the green iron concentrate pellets carried Llthercby, and the carriages 12 are spaced close enough together during travel along the furnace, to avoid the leakage of pellets through the space between the adjacent ends of the carriages, and the grate sections carried thereby.

It should further be understood that the portion of the grate sections through which the hot gases pass are subject to the extreme temperatures while the flanges 22 of the end frame members on the rails 23, 2.3 are protected by said rails, and do not heat up like the grate fingers and their supports.

lt may lbe seen from the foregoing that an improved grate has been provided, which greatly lengthens the life of the grate over the forms of grates heretofore in use, by the simple expediency of isolating the grate fingers from their supports, and allowing the grate fingers to expand free from their supports.

It should also be understood that while I have herein shown two support bars 20, 20 and grate fingers 29, 29 to a grate section, that the two support bars need not necessarily be used and the grate sections may be made with a single support bar and set of grate fingers or with any number of support bars and rows of fingers desired, in accordance with particular requirements.

It should also be understood that the fingers may be of various forms to most efficiently support and convey the material being heated and that the material may be of various materials, in addition to iron concentrate pellets.

While I have herein shown and described one form in which the invention may be embodied, it may readly be understood that various variations and modifications in the invention may be attained without departing from the spirit and scope of the novel concepts thereof.

I claim as my invention:

1. A grate comprising,

a pair of parallel spaced laterally extending end frame members,

at least two laterally spaced longitudinally extending support bars connecting said side frame members together and extending therebeneath,

a plurality of longitudinally spaced laterally extending grate fingers spaced above each support bar and extending to each side thereof,

and support legs extending upwardly of said support bars and supporting said grate fingers on their upper ends and isolating said grate fingers from said support bars.

2. A grate in accordance with claim 1,

wherein one of said end frame members is transversely slit between said support bars entirely through said end frame member to accommodate expansion and lcontraction of the grate.

3. In a traveling grate and in combination with a traveling carriage forming a support therefor and having parallel spaced grate support rails extending transversely thereof,

a grate section supported on said Irails including a pair of parallel spaced grate finger support bars extending longitudinally of the carriage,

parallel end frame members at opposite ends of said support bars and disposed thereabove,

said support bars extending beneath said end frame members to have retaining engagement with the undersurface of the rail,

a plurality of parallel grate fingers supported on each support bar,

and individual legs extending upwardly of said support bars for supporting said fingers on said support bars in vertically spaced relation with respect thereto, to extend to each side thereof.

4. A grate in accordance with claim 3 wherein one of said end frame members is slit to enhance expansion and contraction of the grate scction.

5. In a traveling grate and in combination with a travel- 5 6 ing carriage forming a support therefor and having paralone of said end frame members being transversely slit lel spaced rails extending thereacross, between said cross bars entirely through said side a plurality of grate sections supported on said rails in frame member to compensate for expansion of the side by side relation with respect to eaoh other, grate,

each including a series of parallel longitudinally spaced 5 lingers extending laterally of the carriage,

an end frame member supported on each rail and eX- tending along said rows of grate fingers in spaced relation with respect to opposite sides thereof, and also extending downwardly along the insides of said lo and said grates being supported in side by side relation on said carriage with the slit portions of the next adjacent grates alternately extending along and supported on opposite support rails.

References Cited by the Examiner rails, a pair of parallel laterally spaced cross bars connect- UNITED STATES PATENTS ing said end frame members together and extending therebeneath and forwardly and rearwardly of said 1'098035 5/1914 Greenawalt 266q21 fingers for retaining engagement with the undersur- 15 1,455,040 5/1923 BTOWH 11o-40 face 0f said rails, 2,985,440 5/1961 KOOntZ 266-21 a plurality of parallel legs extending upwardly of said 2,997,287 8/ 1961 Boron 266-21 cross bars and having said fingers supported thereon at their upper ends and isolating said lingers from KENNETH W. SPRAGUE, Primary Examiner. said cross bars, 20 

1. A GRATE COMPRISING, A PAIR OF PARALLEL SPACED LATERALLY EXTENDING END FRAME MEMBERS, AT LEAST TWO LATERALLY SPACED LONGITUDINALLY EXTENDING SUPPORT BARS CONNECTING SAID SIDE FRAME MEMBERS TOGETHER AND EXTENDING THEREBENEATH, A PLURALITY OF LONGITUDINALLY SPACED LATERALLY EXTENDING GRATE FINGERS SPACED ABOVE EACH SUPPORT BAR AND EXTENDING TO EACH SIDE THEREOF, AND SUPPORT LEGS EXTENDING UPWARDLY OF SAID SUPPORT BARS AND SUPPORTING SAID GRATE FINGERS ON THEIR UPPER ENDS AND ISOLATING SAID GRATE FINGERS FROM SAID SUPPORT BARS. 